I'd give it a try but with a very close stop and a first target around the May high. And a tight time stop. Yes, you are right. The spread is already trading high but following nicely its seasonal pattern.
STIRS and Grains Intramarket forward curve has also been sensational. We do a lot of Futures Butterflies and Condors at different places in the Curve. Trades like the Cracks and the Crush have been an afterthought to me the past few years quite frankly. There is safer, better risk/reward to be had.
I know you are trading some complex spreads. However, liquidity can be a problem always. The following is a picture of NGX22-NGZ22-NGF23 butterfly DOM screen captured right before and as you can see liquidity is not very good...